Android Open Source - my_training Numbers Calculator

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License

The source code is released under:

GNU Lesser General Public License

Java Source Code

package com.example.numberscalculator;
//w  w  w  . ja v a 2  s  .  co  m
import java.util.Vector;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class NumbersCalculator extends Activity {
  private String TAG = "NumbersCalculatorDebug";

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_numbers_calculator);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.numbers_calculator, menu);
    return true;
  }

  public void onDigitButtonClicked(View view) {
    Button btn = (Button)view;
    TextView resultedText = (TextView)findViewById(R.id.ResultView);
    if (btn != null && resultedText != null) {
      if (resultedText.getText().charAt(0) == '0' ) {
        resultedText.setText(btn.getText());
      } else {
        resultedText.append(btn.getText());
      }
    }
  }

  public void onOperationButtonClicked(View view) {
    Button btn = (Button)view;
    TextView resultedText = (TextView)findViewById(R.id.ResultView);
    if (btn != null && resultedText != null) {
      CharSequence str = resultedText.getText();
      switch(str.charAt(str.length() - 1)) {
      case '+':
      case '-':
      case '/':
      case '*':
      {
        // new operation is entered. Override last operation
        str = str.subSequence(0, str.length() - 1);
        resultedText.setText(str);
        resultedText.append(btn.getText());
        break;
      }
      default: // if last character was a digit we can simply append an operation.
        resultedText.append(btn.getText());
      }
    }
  }

  public void onEraseButtonClicked(View view) {
    TextView resultedText = (TextView)findViewById(R.id.ResultView);
    if (resultedText != null) {
      CharSequence str = resultedText.getText();
      if (str.charAt(0) != '0') {
        str = str.subSequence(0, str.length() - 1);
        if (str.length() == 0 ) {
          str = "0";
        }
        resultedText.setText(str);
      }
    }
  }

  public void onEqualButtonPressed(View view) {
    TextView resultedText = (TextView)findViewById(R.id.ResultView);
    if (resultedText != null) {
      Vector<String> numbers = new Vector<String>();
      Vector<String> operations = new Vector<String>();
      String expressionStr = resultedText.getText().toString();
      StringBuilder number = new StringBuilder();
      while (expressionStr.length() > 0) {
        switch (expressionStr.charAt(0)) {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
        {
          Log.d(TAG, "char is " + expressionStr.charAt(0));
          number.append(expressionStr.charAt(0));
          Log.d(TAG, "new expression str is " + expressionStr);
          break;
        }
        default:
        {
          if (number.length() > 0) {
            numbers.add(number.toString());
            number = new StringBuilder();
            if (!operations.isEmpty() &&
                numbers.size() >= 2) {
              // Let's count a result for two last numbers
              // if * or / were previous operations.
              if (operations.lastElement().startsWith("*")){
                operations.removeElementAt(operations.size() - 1);
                int result = Integer.parseInt(numbers.lastElement());
                numbers.removeElementAt(numbers.size() - 1);
                result *= Integer.parseInt(numbers.lastElement());
                numbers.removeElementAt(numbers.size() - 1);
                numbers.add(String.valueOf(result));
              } else if (operations.lastElement().startsWith("/") ) {
                operations.removeElementAt(operations.size() - 1);
                int result = Integer.parseInt(numbers.lastElement());
                numbers.removeElementAt(numbers.size() - 1);
                result /= Integer.parseInt(numbers.lastElement());
                numbers.removeElementAt(numbers.size() - 1);
                numbers.add(String.valueOf(result));
              }
            }
          }
          operations.add(String.valueOf(expressionStr.charAt(0)));          
          break;
        }
        }//switch
        expressionStr = expressionStr.substring(1);
      }
      if (number.length() > 0) {
        numbers.add(number.toString());
      }
      // now let's count resulted value
      while (!operations.isEmpty() &&
          !numbers.isEmpty()) {
        int result = 0;
        switch(operations.firstElement().charAt(0)) {
        case '+':
          operations.removeElementAt(0);
          result = Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          result += Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          numbers.insertElementAt(String.valueOf(result), 0);
          break;
        case '-':
          operations.removeElementAt(0);
          result = Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          result -= Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          numbers.insertElementAt(String.valueOf(result), 0);
          break;
        case '*':
          operations.removeElementAt(0);
          result = Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          result *= Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          numbers.insertElementAt(String.valueOf(result), 0);
          break;
        case '/':
          operations.removeElementAt(0);
          result = Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          result /= Integer.parseInt(numbers.firstElement());
          numbers.removeElementAt(0);
          numbers.insertElementAt(String.valueOf(result), 0);
          break;
        default:
          Log.e(TAG, "ERRROR, WRONG OPERATION CHARACTER");
          break;
        } //switch
      } //while
      if (numbers.isEmpty()) {
        Log.e(TAG, "NUMBERS VECTOR IS EMPTY!");
      } else {
        resultedText.setText(numbers.firstElement());
      }
    }
  }
}

Java Source Code List

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